Telephone-exchange system



GfE. MUELLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATIONFILED JUNE 20, 1908.

1,391,136, 7 PatentedSept. 20, 1921.

10 SHEETS-SHEET 1- G; E. MUELLER.-

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 20.1908.

1,391, 1 36.- nte Sept- 20, 1921.

10 SHEETSSHEET 2.

G. E. MUELLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 20, I908.

Patented Sept 20, 1921.

10 SHEETS-SHEET 3.

G. E. MUELLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 20, 190B.

Patented Sept. 20, 1921..

0 SHEETS-SHEET 4.

v G. E. MUELLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 20, 1908.

PatentedSept. 20, 1921. q 10 SHEETSSHEET 5.

v 'G. E. MUELLER.

TELEPHONE EXCHANGE SYSTEM. APPLICATION HLED JUNE 20.1908.

- 1,391,136. PdtentedSept. 20,1921.

l0 SHEETSSHEET 6.

.7; :5 WWW/g .f W -WV G. E. MUELLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FlLED JUNE 20, 1908.

v Patented Sept. 20, 1921.

10 SHEETSSHEET 7.

G. E. MUELLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 20,1908.

PatentedSept. 20, 1921 10 SHEETS-SHEET 8.

e. E. MUELLER. TELEPHONE EXCHANGE SYSTEM.

' APPLICATION FILED JUNE 20, 1908. v I 1,391,1 36, PatentedSept. 20, 1921.

I0 SHEETS-SHEET 9.

G. E. MUELLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 20, 1908.

Patented Sept. 20,1921.

H] SHEETSSHEET 10.

UNITED STATES- T NT OFF CE.

GEORGE E. MUELLER, 0E AURORA,-ILLINOIS, ASSIGNOR, BY MESN 'E ASSIGNMENTS, TO KIElLLOGrG' SWITCHBOARD 8c SUPPLY COMPANY, A CORPORATION OFILLINOISI TELEPHONE-EXCHAITQE SYSTEM.

I Application filed June 20,

T 0 all whom it may concern: V

Beit known that. I, GEORGE EQMUELLER, a citizen of the United States, residing in Aurora, in the county of Kane and State of Illinois, have invented new and useful'Improvements in Telephone Exchange Systems, of which the following is a specification. i

My invention has to do with automatic and semi-automatic systems and I have elected to illustrate the same as embodied in the system of the latter class.

The invention is directed to a system wherein selective switches are employed to interconnect subscribers telephone lines for conversation so organized that impulse transmitters at the subscribers stations are unnecessary. To do this, I provide a number of operators positions atthe exchange, each having included: in its apparatus, one or more impulse transmitting devices to be actuated by operators. Iamfaware that systems of this general charac'terhave hereto fore been proposed and the present invention is directedtoward certain improvements in such systems. An object of thepresent invention is to provide means for automatically connecting.

the circuits at the exchanges over which con- 'nections are to be completed, with idle-op erators calling devices, and then automatically disconnecting thecircuits' from such devices to render them availablefor further use as soon as the impulses'have been trans mitted. The connection of the exchange circuits with the calling devices may be'automatically effected in a variety'o'f ways, and I have illustrated two general ways in which this may be accomplished, oneway requiring the use of selecting switches to effect the connections, and the other accomplishing the result by means of relays.

Another objectof the invention is to provide, in combination with the before indi cated' system, an improved operators transmitting device. In the organized system of my invention, a plurality of impulsejsets must be transmitted to complete each connection, for instance, oiie-set'representing the thousands, another set the hundreds, and other sets the tens and unitsf Assumingfa maximum of ten impulses per set, ten buttons will be: provided preferablynumbered specificationof Letters Patent. Patented Sept, 20', 1921.

1908. Serial No. 439,582';

according to the number of impulses they are adapted to transmit. Diflt'erent buttons may serve to transmit the four sets of impulses required for a connection according to the digits of the number to be transv mitted, or in case each set of impulses should be of the same digit value, as for example- 3383, the 8 button will be depressed by the operator four times. ployed mayoperate in the mannerof the customary order wire buttons, being actu ated' by an operator and immediately re- The buttons emstored when released. Thus, a simple imwith my; invention. Fig. 2 illustrates a circuit adapted for employment when trunking between exchanges is employed. Fig. 3 illustrates a modified first selector circuit and its auxiliary mechanism. Figs. 4 and 5 illustrate other modifications of first selector circuits; Fig. 6 illustrates a modified operat-ors impulse transmitter arrangement. Figs. 7, 8 and 9'are elevations of a selective switch which may be employed in connectionwith'thecircuits of my invention; Fig. 10 shows detail of the'primary off-normal switch of said selective switch. Fig. 11 is a sectional view showing in detail the arrangement of aprimary magnet, with its associated mechanism,v of'said selective switch.

I Referring first to Fig. 1, Parts 1, 2 and 4, are to be placed in the order indicated with Part 1 at the left, Part3 being placed immediately above Part 2 to constitute a complete'circuit diagram illustrating a preferred embodiment of the invention.

The sheets bein'garranged in the way indicated,- it will be observed that at G and D, I have indicated two substation telephone circuits of well known character "whereof C in the present description will be the calling substation and D the called substation. The instrumentalities employed in completing a connection between the calling station C and the called station D will include a line selector E which starts its traveliupon the initiation of a call at substation C and automatically picks out the calling line. Simultaneously with the starting of the switch E, another automatic switch F paired with the switch E starts into operation and automatically selects an idle first selector H. Thereupon, the switch K associated with the first selector H, has its circuit connections changed so that a signal pertaining to an operatorsimpulse transmitter will be displayed at the operators position, the circuits of one transmitter being shown in Fig. 1,

' Part 3. It maybe stated at this time that ple contacts of such transmitting device he .the switches K, one of which is provided for each first selector H, have before their wiper contacts 128, 129, 130, 131, multiple con tacts 132, 133, 134 135, each set of multiple contacts being connected to a different impulsetransmitter and the signal associated with it. When the first selector H is idle, the wipers of' its associated switch K will rest engaging the multiple contacts of an idle transmitting device. Should themultimade busy, the wipers of the switch K will be automatically moved free from the contacts of the then busy device and will seek out contacts of an idle device.

When the calling linehas thus been extended to an impulse transmitting device, thecallsignal associated therewith will be displayed and thebperatorobserving the signal, ascertains the want of the calling subscriber, and actuates the buttonsjof the calling device to count out the called subscribers number; whereafter the impulse transmitter; automatically. transmits the proper impulses to adjust directively operable switches to connect with the called for line. In the present instance, a ten thousand line system is illustrated, in which'case first selectorsH are employed to select the thousands, second selectors L to select the hundreds, and the connectors M to select the tensand units. Each first selector H has beforeits wipers 119, 120, .121, a plurality of groups of multiple contacts 166, 167, 168, each groupforming terminals of second selectorsL assigned for connections to a different thousand. Further, each second selector L has before its wipers 180, 181, 182,

"contact sets forming multiple called terminals of subscribers lines. There are preferexchanges.

ablyten groups of contact sets, each group including ten sets, the groups being arexchange or they may be divided so as to.

terminate among a number of different exchanges. Preferably, however, in; any case,

all the operators positions are to be placed in a single locality, as this will materially decrease the expenses of operation as compared with a system in which it is necessary to provide operators quarters in a number of places.

Assuming now a system having eight thou- Z sand subscribers lines, divided among four different exchanges, there .being thus two thousand lines in each exchange, and assuming further that all operators transinit-' ting devices are to be placed in one of these exchanges, a preferred arrangement is as follows: The subscribers lines of each exchange will have assigned to them, ascalling lines, a suitable number of first selectors H together with a suitable number of pairs of switches 'E and F to interconnect the said calling lines with the first selectors. The first selectors H would have before their wipers 119, 120, 121,'not' only terminals of groups of second selectors forconnections with the two thousand lines terminatmgin that exchange, but would also have before said wipers", groups of terminals'of trunk lines extending to second selectors in each of the threeother exchanges. In this Way each first selector H may be operated to pick out local trunk lines for connectionwithin the exchange, or to pick out longtrunk lines extending to any desired one of' the other As before indicated, of the exchange" now under consideration, has its associated individual switch.K connected with the wires 136, 137, 138, 139; these wires, assuming that the operators exeach first selector I1 change is not the one now under corisidera t1on, are long conductors extend ng from the exchange now under consideration 'to the operators exchange. For eachvconnection to be completed, a t-runkline consisting of wires 136, 137, 138, 139, will be used for a short space of time only, namely, long enough for the operator to ascertain the number of the called-for subscriber and for the calling device to automatically count out the digits of the called number whereupon,

"as before indicated, the calling device and thetrunk line including the wires 136, 137, 138, 139, are instantly freed. Thus, while:

each trunk to the operators position as illustrated,requires fourconductors (although the invention is not limited to the particular I arrangement shown), a very small number of such trunk circuits will sufiice to handle a large number of calls on account of the short use required for each call.

Referring now to the exchanges of two thousand lines each, the two thousand lines of the exchange, at which the line of calling subscriber C terminates, are preferably divided as calling and called lines into twenty groups of one hundred'lines' each. Each group of one hundredlines would, on the usual ten per cent. basis,ihave ten connectors M assigned .for making connections therewith. As calling lines, each one hundred line group would have ten line selectors E common to the group and of course an equal number of paired automatic switches F. The first selectors H of which there would be preferably two hundred, would be divided into two groups of one hundred each and their multiple contacts 81, 82, 83, would appear before the wipers 76, 77, 7 8, of one hundred switches F so that each one hundred of first selectorsH would be common toone thousand calling line's. v I V For each one hundred lines as calling lines, the master-switch mechanism G is provided which serves whenever one of the lines initiates a call to startthe switch of an idle pair EF whereof the switchE will select the calling line and'the switch Fwillfiselectthe idle first selector H. r 1

' Assuming that the calling subscriber C desires his line to be'conn'ected'for conversation with that of the. called subscriber D whose line will for the present he assumed to terminate in the same'exchange as that of C and'whose numberis 1233, the calling subscriber C removes his receiver from its hook whereupon hook lever lOris'es in the customary manner and closes a conductive bridge at the substation. Circuit may there upon be traced from ground through the line relay 13, normal contact 18, line limb 12, raised hook-lever 10,'returning over line limb 11, contact 21, to batteryB. The multiple contact sets 26, 27, 28, of the subscribers lines at the line selectors E are normally unselectableowing to the private contacts 26'being grounded through normal contacts Hand 14-. On the operation of relay 13,

armature l l is attracted, removing ground from the private contacts'26 of the calling line C at the line selectors, thus rendering them selectable, andsaidarmature 14:, by engaging its ;-front contact, operates a sub group relay 25 over the common conductor 31 whereby the relay 25 attracts its armature and ungrounds the multiple group contacts 29 of the sub-group atfthe line selectors. The relay 13, by 'armatl'ire '15, places ground upon the multiple private called contacts 22 of the calling line rendering them. busy against incoming calls; Armature 16 of relay 13 disconnects the relay from the calling line and locks the same in series with the master-switch relay 36 over thecommon conductor 35 which has one hundred branches, one to each line relay of the one hundred lines which the master-switch serves.

The line selectors E are preferably doubleacting switches'of the type illustrated in Figs. 7 to 11 having before their wipers '30, 31, 32, one hundred sets of multiple calling contacts 26, 27, 28, arranged in ten groups of ten contact sets each. It 1 is therefore necessary, when the line selector E is started. in its travel, to first select the sub-group in which the calling line is located and thereafter select the calling line .out of the previously selected group. Fo-r. the purpose of controlling the line selectors travel in selecting the group, each sub-group of ten lines has a group relay 25 controlling the multiple group contacts 29 for that subgroup. To engage with the contacts 29, a group selecting wiper 33 is provided which controls the travel of the started line selector E in selecting the group, said wiper 33 moving with the wipers 30, 31, 32, on their pri-' marytravel.v When the wiper 33 engages anungrounded contact 29, the primary travel of the line selectorE ceases and wipers 30, 31, 32, have then selected the subgroup in which the calling line has its contacts; Thereafter the said wipers 30, 31,. 32, begin traveling in an intersecting plane, while the wiper 33 remains motionless,;to pick out the calling line.

' Before proceeding with a further description of the circuits, I will'briefiy refer to the mechanical drawings. of Figs. 7 to 11 which. illustrate more specifically'a line selector, although the same mechanism is adapted for the switches F and also for the first andjsecond selectors and the connectors used in the system.

In the side elevation of Fig. one group of ten contact sets is illustrated, each set consisting of three contacts 26, 27,28. In Fig. 8,-showing the front view of a contact bank, each set is represented by a single short line, this view, therefore, disclosing ten groups of ten contact sets each. As indicated, the Contact setsarearranged as if projecting through the inner surface of a section of. a sphere. The wipers 30, 31, 32, are first adjusted in a rotary direction from left to right a series-of'steps, each step bringing them beneath a different group'of contact sets. W hen a proper group has thus been selected, the ends of the wipers 30, 31,

extremity the group wiper 33 is-mounterh] the group contacts 29 being inserted in'the base of the switch bank, one contact 29 being provided for each vertically extending .groupof contact sets. The wipers 30, 31, 32,

are pivoted in the primary shaft PS and have a rearwardly extending partwhich engages a broad piece mounted upon the secondary shaft SS. The primary motion of the wipers to select the group is accomplished by rotating the primary shaft PS,

while the secondary travel of the wipers is accomplished by moving the secondary shaft SS down, wherebythe switch wipers are rotated. in their pivoted bearing in the shaft PS.

Fordriving the primary shaft PS, a primary magnet PM and an actuating pawl 700 (see section Fig. '11) is provided, the said pawl being arranged to engage successive teeth of the ratchet shown attached to primary shaft PS. A retaining pawl 701 engages teeth of said ratchet and holds the same against back movement under the influence of the spiral sprin 706. Successive actuations of magnet PlVf prevail to move the'ratchet, shaft and wipers step-by-step from left. to right. The piece upon the secondary shaft SS engaging. the rearwardly extending portion of wipers 30, 31, 32, is sufliciently broad so that it remains in engagement with said part of the wipers in whatever position they may be adjusted laterally.

After the primary adjustment of shaft PS, the secondary magnet SM is actuated a number of tunes, each actuation producinga stroke of pawl 702which engages succesprimary shaft PS. It will be noted that the extension 709 of shaft SS when at normal,

' sive teeth in its associated ratchet on shaft SS, said shaft being thusmoved step-bystep downwardly, the retaining pawl 703 holding the same against back movement which would otherwise occur under the in fiuence of spring 707 acting upon the pivoted arm708 which loosely engages a screw threaded to shaft SS, as indicated in Fig. 9. Each step of shaft SS will obviously move the contact ends of wipers 30, 31, 32, a step upwardly and with each step they engage a different contact set of the previously selected group. 7

After the wipers have been adjusted and are to be restored to normal, the release magnet RM is actuated. Its attracted armature-704 then engages an end of the pivoted retaining pawl 701 of the primary ratchet. This withdraws-the pawl from the primary ratchet. V Simultaneously therewith the pawl 703 is, by an arm 701 upon the pawl 701, withdrawn from engagement with the retaining ratchet'of shaft SS. Spring707 then avails to raise the shaft SS upward whereby the wipers of the switch are restored as to their secondary travel. Until this occurs, the tension of spring 706 upon primaryshaft PS is unavailing, because of the factthat tooth 705, of the piece 709 is engaging one of the teeth of the ratchet'wheel of as shown in Fig. 9, engages the lower extremity of the piece 709, holding the piece and tooth 705 in a raised position. On the first downward step of shaft SS, the piece 709 is freed and is moved downward by springs 54, 55, so that tooth 705 engages whatever tooth of the primary ratchet it is then opposite. When the secondary shaft 'in the restoring process reaches normal, it

again raises the piece 709, tooth 705 disengages the primary ratchet and the tension of spring 7063is then effective to move shaft PS and'the switch wipers back to normal.

In addition to parts heretofore mentioned, 9

each selective switch includes a primary offnorrnal switch and secondary off-normal switch. As indicated in Fig. 10, the primary ofl' -normal switch (which is indicated throughout the drawings by the letters PON), may include'the springs 47 and 48, the former having an angular bent portion for engagement by the stud 710 mounted upon an arm 711 fastened to shaft PS. Ob-. viously, on the first primary step, arm 711 will be rotated a step, stud 710 will free spring 47, whereupon the two primary offnormal springs, by their tension, will assume their alternate positions. The secondary off-normal switch, best shown in Fig. 9, may

include the actuating springs 54 and 55 provided with a stud'709 normallyengaged by the piece 709, whereby the springs 54, 55, are

held in a. definite normal position. On the first downward step; of shaft SS, as before indicated, the piece 709 frees the secondary off-normal springs54, 55, and they then move, by their tension, to engagetheir alternate contacts. I:

The mechanical structure shownin Figs. 7 to 11 inclusive, may be used without change for. those portions of Fig. 1 indicated by E and F; For the fi'rst and second selectorsv and connectors, a similar switch structure may be employed, it beingunderstood that the primary olf-normaland sec 41,42, 43, normally rest engaging'contacts' 44, 45, 46, of an idle switch pair EF,as hereafter explained, and circuit may now be traced from ground at the armature of relay 39 through contact 38, contact 42,45,

normal contact 47 and primary relay PR of switch E to battery B, energizingv relay PR whose attracted armature 49 connects the relays winding with the group wiper 33. Armature 50 of the relay PR closes a generator circuit for primary magnet PM and primary steps of the line selector E are now produced by said-magnet, moving the wipers on their primary travel until wiper33 engages an undergrounded subgroup contact 29, because the relay PR will continue energized by current over looking armature 49 through wiper 33 and to ground through normal, 71. e. grounded, contacts 29- until the sub-group contact of the group in which the calling line is included is reached; at this time the attracted armature of the group relay 25 allows relay PR to be denergized and its armature retracted, armature 50 then opening the circuit of vmagnet PM and preventing further primarysteps of the switch. On the first .primary step of switch E, the primary offnormal PON contacts 47, 48, were shifted, the. shifting of contact47 opening the initial energizing circuit of relay PR which thereafter remains dependent upon wiper 33 for its continued energization; Circuit may now be traced fromground throu h normal switch contact 50' of relay Pit, through closed contact 48, normal contact 54, secondary relay SRto battery, energizing said relay SR which, by armature 57, connects its winding with the circuit extending to the private wiper 30. Armature 58, engaging .its alternate contact, completes a generator circuit for secondary magnet SM traced through .normal contact 52, so that magnet SM receives actuating impulses, stepping the wipers 30, 31,32, up over the contact sets '26, 27 28, of the selected sub-group seeking a .contact set whose private contact 26 is vundergrounded. Relay S-R will continue energized until wiper 30 engages an ungrounded contact 26 because of the successive. locking circuits established by wiper 30 in engaging successive contacts 26 of lines not calling, said circuits being traceable through normal contacts 19 and 14. As soon, however, as wiper 30 engages the contact 26 of the calling line C the ungrounded condition of such contact causes the deenergization of relay SR and further actuations of secondary-magnet SM will be prevented. The secondary off-normal contacts 54 and 55 were shifted on the first secondary step of vthe switch wipers so that thereafter, relay SR depended upon the circuit through wiper 30 for .its continued energization. The calling line has thus 'beenselected by the line selector :E. a

The trunk selector F was started simultaneously with line selector E by current from ground through the armature ofrelay 39 1 at G, attracted armature 37, contact 4-1-44, primary ofi'morma-l contaQ :61 of W tch F audits pnimaryre y 'P ';-Wh, 1.1 l

then attracted its armature 64 .to close a circuit through primary magnet PM which receives actuations to cause primary travel of the switch F. Armature 63 of the relay PR connects the relays winding with the group wiper 79, and relay PR will continue energized and magnet PM continues to receive actuations until the wiper 79 engages an ungrounded group contact 84 pertaining to a group'of first selectors H having one or more unemployed ones among it. The group contacts 84 of groups of first selectors H in which there s no idle switch are grounded as hereafter explained. Thus, as soon as the wiper 79 engages an ungrounded contact 84, relay PR is 'deenergized, its armature retracted and further actuations of primary magnet PM prevented. The primary off-normal contacts 61 and :62 of switch F were shifted on the first primary step, contact 61' opening the initial energizing circuit of relay PR. which thereafter depended for its continued energization solely upon the wiper 79. On the de'elnergization of relay PR, circuit traced from ground through nor.- mal contact 64, the shifted contact 62, normal contacts 80, and secondary relay SR to battery. Said relay SR" energizes and by armature 72, closes a generator circuit for the secondary magnet SM ltraceable through normal contact 66. Armature 70 of relay SR connects the relays winding with the private wiper 7.6 and the relay SR will continue energized during thesecondary travel of switch until wiper 76 en gages an ungrounded contact 81 which will be one pertaining to an idle first selector H; contact 81 of busy first selectors being characterized by ground connections as hereafter explained. When wiper 76 engages the ungroundedcontact 81, relay SR will be deenergized, its armatures retracted and further actuations of secondary magnet SM prevented, whereby wipers 76, 77, 78, rest engaging multiple contacts 81, 82, 83, of the idle ;first.selector H. The secondary off-normal contacts and 80 of switchfF were shifted on the first secondary step, the shifting of contact 80 opening the initial energizing circuit of relay SR and rendering it dependent for current upon the wiper Immediately following the selection of contacts 81, 82, 83, of first selector H, the relays PR and SR will be energized whether or not the line selector E has completed its selection. If said line selector E has not completed its selection, relay SR will be energized and circuit will then be traceable {from the positive pole of battery A .relay PR normal contact 89, contact v82-77, normal contact-69, wire it, alternate contact56, normal contact 53, alternate contact :59, nor al cen er 74, o tact 788 normal contact 90, relay SR to battery B When, under the circumstances just described, switch E completes its selection, the deenergization of relay SR will close a substitute circuit for relay PR extending through normal contact 56, contact 31-27, normal contact'19 cut-ofl relay 17 to battery, which relay by attracting its armature 18, continues. the circuitof relay PR over the calling line, a return circuit being traceable over limb 11, contact 2832, normal contact at 59, and through relay SR to the negative side of battery B These circuit changes occur without allowing the deenergizations of relays PR and SR On the actuation of relay 17 its armature 19'l0cks said relay via contact 26- -30, armature of magnet RM andnormal contact 57 to ground. The armature 20 of relay 17 opens the locking circuit including relays 13 and 36 and they are immediately deenergized, the dee'nergizations of relay 13 deenergizing the group relay 25 whereby the ground 'is restored to the group private contacts 29. It will be noted that aS soon as switch E 00111 leted its selection, retracted armature 5 places ground via wiper 30 upon the multiple contact 26 so that the contacts 26, 27, 28, of the calling line were rendered unselectable with respect to other line selectors. If the line selector E had completed its selection before .the trunk selector F, circuit changes similar to those just described would have occurred except that the primary relay PR would have received its first energizing current in series with the cut-off relay 17 of the calling line.

As soon as both switches E and F complete their selection, the wipers 41, 42, of master-switch G move away from contacts 44, 45, 46, of the switch pair E F in search of other similar contacts pertaining to an idle switch pair EF, it being understood that each switch pair EF serving a given hundred lines has its contact set 44, 45, 46, at the master-switch G of that one hundred lines. The master-switch G may be a simple rotary switch comprising the customary rotary ratchet, shaft and wipers and a magnet 40 having the customary ratchet driving pawl, the contacts 44, 45. 46, being arranged to form a complete circle. It will be observed that as soon as the two switches E and F have completedtheir selection, circuit is traceable from ground at normal contact 52 of relay RR, through normal contact 58, alternate contacts 55-60, normal contact 71, through contact 4643, relay 39 of master-switch G to battery. Relay 39 thereupon attracts its armature, removing ground from the starting wipers 41, 42, and closes circuit for the stepping magnet 40 which thereupon steps the wipers 41, 42, 43, rotarily over the contacts 44, 45, 46, until they engage contacts of a normal,

0., idle switch pair EF, the contacts 46 of busy swi'tch pairs being grounded over c1rcu1ts similar tothat before described.

The multiple contacts 81, 82, 83, of the.

first selectors H, are preferably arranged in ten groups of ten contact sets each,'be-

fore the wipers of switches F. Each such group of contact sets is'provided with a multiple group contact 84 at the switches F. The contacts 84 of a group are connected to a conductor 84 which may be extended through primary group will be accordingly grounded. To

take care of the condition arising when a first selector H has been selected,but has off-normal (PON) contacts 99, 99, 99 etc., to aground not been moved 011 normal, the relay SR of each first selectoris provided with an .ar. mature having COIlIlQCtlOIlS, adapted when the relay is energized to close a branch circuit about the off-normal contact 99 so that as soon as selector H is selected,the circuit.

of the groupcontact .84 is extendedto the primary off-normal contact 99 of the next first selector in theseries.

As soon as relays PR and SR are operated as before described, circuit is closed as follows: From battery B through primary off-normal (PON) contact 100, normal contact 103, attracted armature 94 of relay PR through normal contact at 1 24, relay 122 to ground, whereon relay 122 attracts its armature and closes'a circuit eX- tending from ground through said relay,

armature 124, contact 131135, over wire 139, switch 140, contact 141, and lamp 143 to battery, lighting said lamp at the operators position to indicate the call. vThe wipers 128, 129, 130, 131, in the form of in.- vention now being described, normally rest engaging the contacts 132, 133, 13 4, 135, pertaining to an idle operators calling device and its associated signaling apparatus. As soon as relay 122 operated, as before described, a circuit was closed as follows: From ground through relay 85, attracted armature 123, contact 130- 134, over wire 138, normal contact 156 and resistance 157 to battery. Ground=through 85 now being placed upon the multiple contacts 134 of the operators device, said contacts 134 will be rendered busy with respect to any other switch K engaging them. Thus, if at this tacts of an idle operators device. As soon as such contacts were encountered, the relays OR would be deene'rgized owing to the absence of'ground-upon he contacts 134 of such calling device and the switches would be arrested.

"The operator observing the display of the call-lamp 143, associated with the calling device shown in Fig. 1, Part 3, actuates levers 155, 155 156, of a listening key, levers 155, 155* then bridging her talking set across the wires 136,137, which extend ing the spring set marked via wipers 128, 129, and contacts 126 and 127 to the first selector H and there termina te in armatures 86 and 87 of relay 85. The shifting of lever 1'56 deenergizes relay 85 by disconnectingbat'tery from conductor 138and retracted armatures 86 and 87 connect the operators talking set with contacts 82 and 83 over which a talking circuit may be traced to the calling substation C over the heavily marked conductors, such heavily marked conductors bein'g'emplo'yed throughout the drawings to indicate the course of the talking circuit established between sub scribers. The operator now ascertains from the calling subscriber the number of the wanted called subscriber assumed to be 1233,

vand releases once the button actuating the spring set marked 1 in Fig. 1, Part 3; then presses and releases the button actuating the spring set marked 2 and then presses and releases twice the button actuat- 3. In the diagram of. Fig. 1, Part3, those parts of the mechanism pertaining to the thousands are indicated by reference characters employing the letter M; those parts relating to the hundreds are identified by the reference character letter C; the tens by D and the units by U. For each thousands digit to be transmitted, a relay is provided, the relay M being the relay controlling the transmission of the thousands digit 1, the relay M controlling thetransmission of the thousands digit 2, and the relay M controlling the transmission of the thousands digit 3. For

each number 4,5, 6, 8 a'nd 9, if such jth'ousands digits were required, an additional relay would be providedhaving circult n ction? W PQSP Qd 9 t e 9f the relays M, M M as shown in Fig. 1, Part 3. Thus, the thousands digit relays will constitute a group. Similarly, for the hundreds, C is the relay for the hundreds digit 1, C for the hundreds digit 2, and C for the hundreds digit 3 and other relays will be provided, for the other hundreds digits to be transmitted, the hundreds relays forming the second group. Similarly, relays D, D D are the relays for the tens digits 1, 2, and 3, and relays U, U U for the units digits 1, 2, and 3. The alternate contacts of spring 1", 2 3", etc., of the operators buttons are connected to wipers 160, 160", 160, etc., of an auxiliary switch 2 All of the wipers 160, of which there will be as many as there are digits to be transmitted, normally rest engaging contacts M connected to the thousands relays of their respective digit values. WVhen as in the present instance, the thousands digit is 1 and the button actuating the springs 1 1", is operated, the relay M controlling the transmission of the thousands digit 1 will be en ergized and thereafter the wipers 160 will all simultaneously move to engage their second contacts, those connected with their respective hundreds relays, so that the spring sets 1, 2, 3, 4, etc., will then be all connected to'their respective hundreds relays. When the button actuating the spring 2 is now 0 erated, the relays (3 controlling the trans,- mission of the hundreds digit 2, will be en.- ergized and the wipers 160 will all be moved to the contacts D connected with the tens relays D, D D etc.; then when the operator actuates the button controlling the springs 3 which will energize the tens relay D controlling the transmission of tens digit 3, the wipers 160 will all be moved to the contacts U connected with the units relays U, U U thereafter when the operator again depresses the button controlling the springs 3, the units relay U controlling the transmission of units digits 3 will be energized and the wipers 160 move an additional step. The apparatus being now,-by the operation of the required relays, in the thousands, hundreds, tens and units groups set for the transmission of number l233, the

through contact 160M, through relay M to battery, said relay M then attracting its When the operator acc armature and locking itself via said armature m, contact r?) and contact 142 to ground. Armature m also connects the ground at 142 with relay M which operates to attract armature m to lock itself to ground at 142 and armature m similarly operates relay M whose armature m locks the relay to ground at 14-2. Armatures 972-, m m have now removed ground at 142 from the first three contacts M before the wiper 150 so that the fourth contact only remains grounded and but one impulse will be transmitted over wire 136 when wiper 150 passes over the contact M in the manner presently to be described. The closing of contact l for a moment energizes and deenergizes the operating magnet of switch 2 and the armature controlled pawl 153 of said switch, on the deenergization of magnet 0 steps its associated ratchet one step. Said ratchet is fastened to the shaft 159 to which also the wipers 160 are fastened so that the said sands relays remain unaltered as they are all locked as before described.

The operator now depresses and releases the button for spring set 2 whereon springs 2* and 2 momentarily engage their contacts. Circuit is then traceable from ground through spring 2 over 165", contact 160 -C, relay C to battery. Relay C attracts armature 0 thereby locking itself from ground at contact 142 of switch 3*. Armature 0 also connects said 'round with the winding of relay 0 which looks. It will now be observed that the first two contacts C" have been, by the operation of armatures c c ungrounded. The contact C connected with armature 0', however, remains grounded and since the last contact C is permanently grounded, the wiper 150 when it passes over the hundreds contacts C, will transmit two current impulses from ground over the wire 136. The momentary closing of contact 2 energizes and deenergizes magnet 0 whose attracted and retracted armature steps the shaft 159 a step so that wipers 160, 160", and 160 are advanced a step to engage their tens contacts D respectively.

The operator now actuates the button for the spring set 8 twice. On its first actuation, current flows from ground through spring 3, over 1655, contact 160 D, relay D to battery, said relay D by armature (i then locking itself to ground at contact 142. The armature d removes ground from one contact D only in the tens mit three impulses from ground over wire 136. The first actuation of the button controlling the spring set 3 will, in an obvious manner, produce a third step of wipers 160, 160 160, so that theywill engage their fourth contacts U. r

The next actuation of the button controlling the spring set 3 will close circuit from ground through springB", through contact 16O U, and through rela-ylU whose armature a locksthe relay and removesground fromthe first one of the contacts U, the

remaining contacts U remaining grounded sothat when wiper 150 passes over said contacts, it transmits three impulses from ground over the wire 186. I p

It will now be seen that when the wiper 150 is caused to make one complete revolu-. tion in the direction indicated by the arrow,

it will pass over the various contacts M, C,

D U, transmitting to the wire 186, sets of impulses corresponding to the number of.

the called subscriber1233. The wiper 149 being mounted on the same shaft 145, moves coincidently with the wiper 150 and as the said wiper 150'passes beyond the last contacts M C D 1), respectively, the wiper 149 will engage respectively the grounded contact, energizes and deenergizes release magnet r ofthe switch 2 and the attracted armature 164 is effective to withdraw the pawl 163 from the ratchet of shaft 159 and its associated spring now restores the shaft 159 and the wipers 160 tonormal. The engagement of spring S 'with its'contact, closes circuit from ground over 165 through magnet O of switch 3* and an impulse from the associated generator actuates magnet O to advance the ratchet 148, fastened to shaft 145, a stepa The spring 146has a bent eX- tremity normally engaging the notch in the dislrshown fastened to shaft 145. first step of shaft 145, spring 146 rides upon the periphery of the disk and engages its contact, whereby the generator circuit of magnet O is continued when the momentary closing of contact S ceases. It will now be apparent that until the armature actuated pawl of magnet O has been operated a sufficient number of times to cause a complete revolution of ratchet 148 and shaft 145, contact 146 will remain closed, the magnet O will receive successive impulses from the associated generator. As soon as one complete revolution is made,however, spring 146 again engages the notch of its associated On. the

disk and travel of the switch 3 ceases. The

wipers 149, 150 being fastened to shaft as before indicated. Just before the switch 3 "completes its will, of courseybe rotated along with'the rra'tchet 148 andwill have completed one revolution when the switch-3 .stops,"1m-

pulses being transmitted over wires 136, 137,

revolution, an insulating pm .147- fastened in the disk mentioned, Wl'll pass over the top of the bent portion otspring 142, opening contact 142, and also contact 141. The open-v ing of contact 142 unlocks all-the relays M, C, D and U, that were energized and thus restores this portion of the calling device to normal. Theopening of contact 141termi-' nates the flow of current previously passing from battery through lamp 143, over wire 139, contact 135'131,- the attracted arma-,

ture 124 and relay 122 to ground," whereby the relay 122 is deenergizedand its armatures retracted, and the lamp 143 extinguished. The" relay 122 is not again energized because 'the' first step of first selector H will have opened the primary off-normal contact 100. On the retraction of armature 123 of relay 122, ground is removed from the multiplecontact s 134 so that any other switch K, which in its travel'engage's the contacts 132, 133, 134, 135, may come to rest engaging such contacts. The apparatus of:

the operators' calling devi'ce,--illustrated in Fig. 1, Part3, has-now been fully restored to normal and its associated trunk wires 136, 137, 138, 139, are now available for further use in putting through other connections;

At? in Fig. 1, Part 3, I have indicated a spring 'set comprising springs 1 and r", This spring set, when actuated, will restore the switch 2 and'any relays M, C, D, U, that may then be operated to normal, and is provided for the p'urposeof resetting'the apparatus in case the operator may make a mistake in counting out the called number.

I have indicated at 165, 165*,165, 165 and 165 switch'levers which may all be mounted upon a common shaft 165.. turningthe shaft 165, a, single operators set of buttons 1,2, 3, etc.,may be interchangeably associated with diii'erent calling vdevice switches in an'obvious mannerQ Preferably,

however, each calling device; is provided with a separate set oi actuating buttons.

f It will be observed that the spring 4 is not provided with any associated contact and thus when the spring set 4 is actuated, no digit relaywill'be energized. It will be seen that for transmitting the largest digit of any set, all the contacts before the wiper 150 for-that impulse group are to .be left in their normal grounded conditions. the present case, the impulse transm tter is arranged to transmit a maximum offour vimpulses.

lVhen the device is arranged to V transmit sets of, impulses from one to ten inclusive, there will of course be relays for each' of the digits from one to nine mclus sive, the button 10 having connectionsthen arranged to correspond with those of button 4 indicated in Fig. 1, Part3.

' fgThe method in which the first selector 1 the. second selector L and the connector M operate'in response to theim'pulses transmitted by the mechanism in'Fig. 1, Part 3, will now be described.

The first set of impulses transmitted, when wiper 150 moved over contacts'Mfl con- 13 6, contact 132128,' contact 126, "alternate contact 86, relay PR to battery, actuating'saidrelay whose attracted armature first closed a maintaining circuit for secondary;

relay SR 1 extending through contact 90, attracted armature 88 and alternate contact 89, whereafter normal contact 89 is opened. and relay PR momentarily. deenergized. Onthe deen'ergization of said relay, its armaturesretract and an impulse of cur-' rent is transinitted'fr'om ground through attracted armature 97, normal contact 92 contact 109,.primary magnet PM to battery,"whereupon' magnet PM moves the switch wipers 119, 120, 121, one primary step .to select the first group of contacts, said group tormingterminals of second selectors L assigned for connection to the first thousand. lViththis first primary step, primary off-normal (PON) contacts 100,101, l10,'are shifted totheir alternate positions. The vimpulse 1 transmitted by wiper 149,

Fig. 1, Part 3, over wire137, passes through circuit of relay SR 'de'e'nergizing the same.

Al current impulse then flows from ground through'attracted armature '93, normal con: tact 98, contact 108, primary off-normal V sisted of one impulse, this passing over wire The armature of relay SR? is Y contact 110, shifted on the primary step,

through busy relay BB to battery, actuating said rclaywhose armature 116 connects itswinding via contact 113 with the private I wiper 119. Armature 117 now closes generator' circuit. for secondary magnet SM which produces secondary steps of the first selectonH which willcontinue until wiper 119 strikes an ungrounded, 6., idle contact 166. As soon as this occurs, relay BB deengerizes and its 'armatures retract, arma:

" ture'117 preventing further actuations of magnet Sl\4 ,-wipers 119, 120, 121,-resting engagingthe multiple" contacts 166, 167, 1.68, terminals o'f the selected idle second selector L of the first thousand. It will be noted that while the wipers 120,121, are passing over busy terminals 167, 168, they are on .zations of relay open circuit at contacts115, 11.8. Armature 116 has placed groundupon multiple contacts 166, rendering them busy.

When wiper 150 passes 'overcontacts C", two impulses will be transmittedover wire 136, energizing and decnergizing relay PR twice, which relavproduces two deenergi PR while relay. SR re mains energized, Each energization of relay PR transmits a. current impulse from ground.through contact 97, normal con tact 92, "contact.115, 120 167, contact170,

magnet PM f' tobattery Magnet PM then. produces two primary steps of second selector L, moving wipers 180, 181, 182, adjacent to .a group o'f-multiple terminals 183,

184, .185, connected to connectors M assigned for connection to thevse'cond hundred of thefirst thousand. .'On the first primary step ofgswitch L, the contacts 179and 169 are shifted. After the transmission of the two impulsesover. wire 136 and the resulting two stepsof switch L, a single impulse over .wire 137 -energizes and deenergizes relay SR which deenergizes relay SR while relayPR- remains operated. .An impulse ofcurrent then flows from ground through .contact 93, normal contact 98, contacts .118,

' 121 -168, 171, contact 179, busy relay BB to battery, actuating said relay which, by

armature 176, connects its winding with the private wiper 180, and by armature 177, closes a generator circuit for secondary magnet SM-lwhich nowcauses steps ofwipers 180, 181, 182, over successive contact sets 183, 184, 185, until an idle, e.,.ung1;oundedset is encountered. Assoon as this occurs, relay BR will be on open circuit and on its deenergization its armatures are recircuit O'fmagnet'SM and by engaging its normal contact, said armature 177 places ground upon the multiple contacts 183 of the idle connector M to render them busy. The wipers 180, 181, 182, now rest engaging the multiple contacts 183, 184 185, of

. the selected connector M. Onv the first sec ondary step of the switch L, the secondary off-normal (SON) contacts 170, 171, were 215, 216, to positions adjacent to a group of ten contact sets includingthose of lines 1231 to 1239 inclusive, followed by contact of'line 1230. On the first primary step of connector M, the primary off-normal ('PQN) contacts trac'ted, armature 177 opening'the generator.

nectorM are produced to move wipers 214,

nate positions. After this adjustment, an

impulse flowing over wire 137 deie'ne'rgizes. relay SR3, an mpulse of current flowing from ground, at attracted, armature [93 through contacts 98, 121 168, 182185,nor-

186, 187, 188, are all shifted to their altermal'contact 218, shiftedc0ntact '188, magnet 9 SM to battery B Ma gnet SMthereupon produces a secondary step of the connector M, but the switch WIPGIS' do not'engage thev first set of contacts of the-selected group, the

connector beingso arranged-that the Wipers after their primary adjustmentfare two steps distant from the selected contact group sonormal contact 217 toy'engage its alternate 1 This first step, however, causes secondary offcontact, while contact 218 disengages itsnor mal contact,but is not moved engage its alternate contact.

As wiper 150, cont nues its rotation pass ing overjthe contacts Ut," three deenergizations of relay PR produced in anobvious manner,- transmits three ,impulses from sufliciently' to ground at contact 97 over the above traced path through contact 181[184, alternate contact 217, normal contact 192, secondary magnet SM* to battery,- whereby three addi tional secondarysteps of connector M are produced, and wipers 2-14, 215, 216, are moved to engage thecont'a'ctsetn22, 23, 24, of

tion is illustrated at D,. Immediately following this,wiper 149 transmits an impulse over wire 137, the resulting decnergization' of relay SR transmittingan impulse of'current from ground at attracted armature 93 over the before traced path, throughcontact 182- 185,. alternate'contact 218 (said contact having been closed on the secondgsecondary step of connector M) ,through contact 196, the lower winding of test relay TB to battery. Said relay thereupon attracts its 95 the third'line of thegroup, said contactsf being terminals of line 1233 whose substaarmatures whereof 206'- connects the relays upper windirag with the private wiper 214 to test the calle 9 for line. Assuming first'that the called line is idle, the condition illustrated, multiple contacts 22 are connected through normal contact 15 andthe winding of cut-oflf relay 17 with the active side of battery B As soon as the. impulse through the lower windingoffrelayTR ceases, the relay will now dener gize, both terminals of its upper winding beinv connected lto the active side of battery 1%.. It will at this.

point. be observed that the impulse through the lower winding of relayTR is momentary only because the attraction of its armature 207 instantly energizes relay 194 by current from battery through said relay, contact 207, normal contact 199, to ground. 'Relay 194,

by armature 195, locked itself to ground at 190 and theattraction of armature-196 at onceopens circuitthrough the lower winding of relay TR. On the deenergization of 

